1. Technical Field
This invention relates generally to keyboards, and, more particularly, to keyboards with indicators.
2. Related Art
Function keys, also called pushbuttons, are standard parts for many types of electronic equipment. Typically, the function keys are plastic parts used to push down on a dome in a rubberized keypad which covers the printed circuit board. A conductive area is present on the reverse side of the keypad. Pushing the key causes the conductive area to touch a printed circuit board, making a connection between two contact points that are normally not connected.
A light emitting diode (LED) is a common source of light for electronic indicators. Lightpipes are often used to conduct LED-produced light from the circuit board to the viewing area. One end of the lightpipe covers the LED and the other end constitutes the indicator, as perceived by the viewer. The lightpipe gathers light emitted from the LED at a wide viewing angle, and transfers the light as a narrow beam of light along the lightpipe to the indicator. Conventional lightpipes are flush with the device surface, commonly referred to as a keyboard, resulting in light which is emitted with a narrow viewing angle perpendicular to the surface of the keyboard. This results in the emitted light not being noticeable until the user is in close proximity to the device. Also, the view of the lightpipe is obstructed by function keys which are raised off the surface of the keyboard.
Lightpipes are usually separated from their associated function keys by the structural supports and guides for the lightpipe and the function key. As a result, it is sometimes not clear which lightpipes are associated with which function keys, especially when there are numerous lightpipes and function keys on a keyboard. Also, the keyboard space which exists between the separated lightpipes and the associated function keys is unusable, thereby reducing the amount of functions which can be supported by a keyboard of a given size.
There have been a number of conventional techniques implemented to overcome these problems. One has been to include the use of additional labeling or markings to clarify the association between the lightpipes and the function keys. This technique overcomes the problem of association but does not rectify the loss of functional space on the surface of the keyboard. In addition, there are extra costs associated with the production of keyboards with labels or markings.
A second solution includes associating the function key to the lightpipe by arrangement; that is, creating a line of keys and a line of lightpipes that have the same center to center spacing. A third technique has been to use thin support mechanisms so that the two elements may be as close together as possible. Though these two solutions have reduced the amount of unusable space, they have not eliminated it.
A fourth solution has been to install the LED or light source inside or near a transparent or translucent function key. This solution sets limits on the key's compactness and may allow the user unwanted glimpses of the product's inner circuitry. Another drawback of this solution is that transparent or translucent material is more costly than opaque material.
In addition to these problems, a conventional function key typically has a constant diameter along the length of its shaft. The function key is guided by a guiding mechanism which comes into contact with the part of the shaft which extends below the surface of the keyboard when the function key is depressed. The function key carries any contamination it is exposed to above the surface of the keyboard to below the surface when the function key is depressed. The contamination then interferes with the operation of the function key.
Also, there are limitations on the arrangement of conventional function keys in their relation to the key pad dome that they are to control. A conventional function key is typically positioned directly over the keypad dome that it controls to transfer the applied force down through the center of the function key to the key pad dome. The area to apply force which results in the function key moving smoothly within its guiding mechanism is referred to as the key push center.
Conventional function keys have a key push center located at the center of the face of the function key. Applying pressure at a point on the function key outside this area results in the function key twisting rather that moving in its guiding structure. This has limited the possible arrangements of the function key and its associated lightpipe with the LED and contact switch on the circuit board.
What is needed is a lightpipe and function key arrangement that o are adjacent to each other to eliminate the need for marking and labeling on the upper surface of the keyboard. The function key and lightpipe need to be as close as possible, reducing the amount of lost surface area on the keyboard. The lightpipe needs to produce uniformly brilliant light from a height which will result in the light not being obstructed by its associated function key. In addition, the lightpipe needs to emit light at a wide viewing angle to be visible from any position.